In a sub-frame i of a Long Term Evolution (LTE) system, transmit power PPUCCH of a User Equipment (UE) on a Physical Uplink Control Channel (PUCCH) is set and defined as follows:PPUCCH(i)=min{PCMAX,P0—PUCCH+PL+h(nCQI,nHARQ)+ΔF—PUCCH(F)+g(i)}[dBm](Reference can be made to the protocol 3GPP TS 36.213 for details).
Where
      g    ⁡          (      i      )        =            g      ⁡              (                  i          -          1                )              +                  ∑                  m          =          0                          M          -          1                    ⁢                        δ          PUCCH                ⁡                  (                      i            -                          k              m                                )                    and g(i) represents a current adjustment value of PUCCH power control.
δPUCCH represents a revision value specific to the user equipment, that is, a Transmit Power Control (TPC) command, which is included in a Physical Downlink Control Channel (PDCCH) carrying the Downlink Control Information (DCI) formats 1A, 1B, 1D, 1, 2A, 2B, 2C and 2; or is encoded jointly with a PUCCH revision value specific to anther user equipment and sent in a PDCCH carrying the DCI formats 3 and 3A, and at this time, Cyclic Redundancy Check (CRC) parity bits are scrambled with a TPC-PUCCH-RNTI (Radio Network Temporary Identifier).
In all states except the Discontinuous Reception (DRX) state, the user equipment attempts to decode a PDCCH carrying the DCI formats 3 and 3A by the TPC-PUCCH-RNTI specific to the user equipment and decode one or more PDCCH carrying the DCI formats 1A, 1B, 1D, 1, 2A, 2B, 2C and 2 by a Cell Radio Network Temporary Identifier (C-RNTI) specific to the user equipment in each downlink sub-frame.
If the UE detects a PDCCH carrying the DCI formats 1A, 1B, 1D, 1, 2A, 2B, 2C and 2, that is, a detected RNTI is equal to the C-RNTI of the UE, then the UE will use δPUCCH provided in this PDCCH; otherwise, if the UE detects a PDCCH carrying the DCI formats 3 and 3A, then the UE will use δPUCCH provided in this PDCCH; otherwise, the UE sets δPUCCH=0 dB.
In an LTE-A system, an eNB will redefine a part of DCI bit information to indicate other information so as not to increase a PDCCH overhead, for example, when DAI≠1 in the DCI formats 1A, 1D, 1, 2A, 2B, 2C and 2, information in a TPC field in the DCI is used to indicate PUCCH resource indication information, and at this time a TPC command word in the DCI formats 1A, 1B, 1D, 1, 2A, 2B, 2C and 2 can not provide power control information.
In summary, the user equipment can not be provided with power control information so far when information in the TPC field is used to indicate a non-TPC command so that the user equipment can not perform PUCCH power control, thus degrading the accuracy of PUCCH power.